Data signalling systems

ABSTRACT

In a security alarm signalling system in which a signal may be transmitted from any one of a number of remote stations to a central receiving station, the receiving station includes a multiple input encoder responsive to a change of state on any one of its inputs for presenting a coded output representative of the number of the input on which the change of state has occurred, and a digital display device including means for scanning the coded output to obtain a digital readout of the said number and thereby, in use, identifying the associated remote station.

United States Patent 11 1 McSorley et a1. 1 1 May 6, 1975 [54] DATASIGNALLING SYSTEMS 3,644,927 2/1972 Green 340/413 3,714,646 1 1973 N b l4 4 [75] inventors: David J. McSorley, Tw1ckenham; um erg er 3 0/ CroosBanstead both of Primary Examiner.1ohn W. Caldwell ng an AssistantExaminerRichard P. Lange [73] Assignee: Alarm Equipment SuppliesLimited, 141mm? g fl, Palmer &

Twickenham, Middlesex, England Estabrook [22] F1led: Apr. 17, 1973 [57]ABSTRACT 1 1 Appl- N04 351,882 In a security alarm signalling system inwhich a signal may be transmitted from any one of a number of re 52 US.(:1. 340/413; 340/150 mote Stations to a central receiving Station thereceiv- 51 1m. (:1. G08b 19/00; H04g 3/00 Station includes a multipleinput encoder respon- [58] Field of Search 340/413, 412, 408, 213.1,Sive a change of State any one of its inputs for 340/150 151, I63presenting a coded output representative of the number of the input onwhich the change of state has 00- [56] References Cited curred, and adigital display device including means UNITED STATES PATENTS forscanning the coded output to obtain a digital read- I out of the saidnumber and thereby, in use, identifying 3,483,555 12/1969 1311310....340/2131 the associated remote Station 3,543,267 11/1970 Morrls 340/4133,613,092 10/1971 Schumann et a1. 340/413 7 Claims, 2 Drawing FiguresMotnx r0 Matrix PATENIEB-" 975 SHEET KE S m5 9 QQNQQE w k m R m KQE MXQR ES DATA SIGNALLING SYSTEMS This invention relates to signallingsystems, and has particular application to a multi-line security alarmsystem in which alarm signals from different remote stations are fed toa central receiving station.

At present the central receiving station normally includes one or moreindicator panels having indicator lights to identify the differentremote station. Such panels are generally bulky. Moreover, with systemshandling a large number of input lines, more than one security officeris often required to maintain adequate supervision of the differentpanels.

In accordance with the present invention a receiver for use in asecurity alarm signalling system in which a signal may be transmittedfrom any one of a number of remote stations to a central receivingstation, includes: a multiple input encoder responsive to a change ofstate on any one of its inputs for presenting a coded outputrepresentative of the number of the input on which the change of statehas occurred, and a digital display device including means for scanningthe coded output to obtain a digital read-out of the said number andthereby, in use, identifying the associated remote station.

In one embodiment of the invention the appearance or disappearance ofinput signals from the remote stations trigger respective bistabledevices, and a gating circuit is connected between each of the bistabledevices and respective inputs of the encoder. The system then includes ashift register for enabling each of the gating circuits in turn andmeans for inhibiting the shift register whenever a signal is transferredinto the encoder. This prevents further signals being transferred intothe encoder before the original signal has been encoded and read out onthe display device. The encoder may comprise, for example, amatrix, eachinput being connected to a pair of mutually perpendicular coordinatelines, and the scanning means then includes a pair of counters arrangedto hunt synchronously along the coordinate lines until a coincidence isobtained for each counter. The two counters then give a combined readout in which the two digits represent the least significant digit andthe most significant digit of the line number on which a change of statehas occured.

One example of the invention is shown in the accompanying drawings inwhich:

FIG. 1 is a block circuit diagram of a multiple line alarm securitysystem which presents a visual digital read-out and prints informationrelating to the date, time and place at which an alarm signal wasgenerated.

FIG. 2 is a waveform diagram illustrating the operation of the circuitin FIG. 1.

Referring to these figures, the appearance or disappearance of an alarminput A,A,, triggers a corresponding pulse stretching circuit Dl-Dnwhich in turn transfers the J-K flip-flops B/Sl B/Sn to a 1.

The flip-flops acts as a binary store and a l in the store istransferred to a preselected address in a matrix through NAND gates Ila, 1 lb, etc., by the appearance of enabling shift registersignalsfl,j2, etc., on the second NAND gate input. A signal istransferred to a particular address in the diode matrix by feeding theoutputs of each NAND gate to a predetermined intersection of thecoordinate lines of the matrix. Each output is thereby connected to thejunction of a pair of forward biased diodes in the matrix so that anoutput is obtained on each of the respective coordinate lines. Thecoordinate address of each store element is selected to correspond tothe number of the input on which the appearance or disappearance of asignal has been detected. For example, the coordinates (3, 4) willcorrespond to line No. 34.

The presence of a 1 in the matrix enables NAND gates G1, G2 from theoutputs of NOR gates 12a 12d and NAND gates 13a, 131) such that pulsesfrom an oscillator S1 are gated to master electromagnetic decadecounters El having decimal read-out wires connected to AND gates 16a,16b. Only two of these gates 16a0 and 16219 (these connected to the 0and read out wires) are shown in the figure for the sake of clarity. Thesecond input of the gates 16a, 16b is connected to the corresponding oneof the 0-9 and 10-90 lines of the matrix. The counters then huntsinchronously along the mutually perpendicular matrix lines until thetwo coordinates are found which give a coincidence output from the gates16a, 16b. The coincidence outputs are fed to OR gates 14a, 1412 whichinhibit the gates G1, G2 respectively to stop the counters. The numberindicated on the counters then corresponds to the number of the input onwhich a change of state has been detected. Ancillary slave counterscontrolling the print wheels of a printer (not shown) are wired inparallel to the master counters so that a visible read out of the finalnumber displayed by the counters can be supplemented by printing thenumber with the time and date at which it occured.

The presence of a l in the matrix also inhibits the shift register bytriggering a control bistable B1 to close a gate G3 between a clock Cland the shift register. This prevents any further signals being readinto the matrix before the original signal has been read out.

The resetting of the flip-flops is controlled by an input from the NORgates 15a 15n. The gates [5a 1511 can only be enabled by the coincidenceof an X input from a 20 micro-second delay circuit D10 responsive to theoutput of bistable B1 and a second input which is connected to therespective matrix store input. In other words, when a particularflip-flop transfers data to the matrix store, only that flip-flop can bereset after the data has been read out. This ensures that if at any timetwo or more alarm inputs appear simultaneously, they will be read outserially.

A complete cycle of operation commencing with an alarm input is clearlyillustrated in FIG. 2. The alarm input triggers one of the J-Kflip-flops B/Sl B/Sn and when the output from the flip-flop nextcoincides with the output of the shift register a pulse is fed into thematrix. The presence of the pulse in the matrix triggers the controlbistable Bl which in turn triggers a timer giving a pulse of between 5and 10 seconds. During this time the master decade counters hunt for theaddress of the stored signal and at the end of the timer period a resetpulse from the delay circuit D10 resets the J-K flipflop. This in turncancels the data in the matrix store.

The signal from the delay circuit D10 also triggers a second m5 delaycircuit D20, and the output from D20 enables a gate G6 to permit theprinting of the final count displayed by the slave counters of theprinter. At the end of the print time a monostable M3 is triggered whichcloses the gates G1, G2 and feeds a reset signal to the electromagneticdecade counters and to the slave counters of the printer. The trailingedge of the pulse from the monostable M3 triggers a 5 ,us monostable M4and the output from M4'resets the control bistable Bl. This enables thegate G3 so that clock pulses are again fed to the shift register.

The shift register also clears the dynamic *bit on every 99th pulse ofthe clock to avoid any trailing pulses.

The appearance or disappearance of line fault inputs LFl LFI triggerpulse stretching circuits DlA-DnA corresponding to the pulse stretchingcircuits D1- Dn so that line fault inputs are displayed in the same wayas the alarm inputs. In order to distinguish between line fault andalarm conditions separate indicators are provided for each condition.Thus during an alarm display. an output from the pulse stretchingcircuits Dl- Dn enables OR gates G7 which triggers bistable B2 toenergize the alarm indicator. During a line fault condition, on theother hand, an output from the pulse stretching circuits D/A-DnA enablesOR gate G7a which triggers bistable 82a to energize the line faultindicator. Further, in order to distinguish between the appearance anddisappearance of an alarm or line fault input the outputs of thebistables B2, 82a are fed to an OR gate G8, and the output of G8inhibits an AND gate G9 connected to a clear line indicator. The secondinput of the AND gate G9 receives a Z pulse output from the bistable Blwhich occurs each time a number is loaded into the matrix and displayedby the counters; if a number is displayed in response to thedisappearance of an alarm input the AND gate G9 will no longer beinhibited because there is no input to the gates G7, G711 and the clearline indicator will therefore be energized by the Z pulse.

In one alternative system (not illustrated) for handling up to 1000input lines. a change of state on any one input line is fed to anencoder which converts the single input into binary coded decimal (BCD)form representing the number of the input. This has the advantage ofrequiring not more than 12 output wires for each input. The BCD outputsrepresenting the most and least significant digits may then either besynchronously scanned to search for the marked lines (this requires adisplay device which is capable of decoding the detected BCD(information) or they may be first decoded back into decimal form andthen fed to AND gates such as those shown as 16a 16b etc., in thedrawing for comparison with the decimal outputs of theelectro-mechanical decade counters.

We claim:

1. A receiver for use in a security alarm signalling system in which apredetermined number of remote stations are each connected to a centralreceiving station by respective pairs of wires. each remote stationbeing identified by a different predetermined number. and the receiverincluding a multiple input encoder, each input of said encoder beingconnected. when in use. to a respective pair of wires from one of thenumbered remote stations. and the receiver also including a multipleinput binary store; gating means connected between the outputs of saidbinary store and corresponding inputs of said encoder; scanning meansfor periodically scanning the inputs of said encoder. said scanningmeans including enabling means for periodically en abling each of saidgating means in turn; said encoder including means responsive to achange in the signal level on any one of its inputs for generating acoded output signal representative of the number of the remote stationto which the input is connected, and a digital display device includingmeans for converting the coded output into a digital read-out of saidnumber; and means responsive to the presence of a signal in said encoderfor inhibiting the enabling means until the signal has been encoded andread out on the display device.

2. A receiver according to claim 1 in which the digital display deviceincludes a counter. and the receiver further includes an oscillator forfeeding pulses to the counter in response to a detected change of signallevel on one of the inputs to the encoder, a coincidence detectorconnected to compare the output of the encoder representing the numberof the remote station associated with the change of signal level withthe number present in the counter. and inhibiting means connected toreceive an output from the coincidence detector when the two numbersbeing compared are equal for inhibiting the supply of pulses to thecounter such that the final number displayed by the counter representsthe number of the remote station.

3. A receiver according to claim 1, further including a clear lineindicator connected to receive an energising signal from a controlcircuit whenever a change in signal level has been detected at one ofthe encoder inputs, and means for inhibiting operation of the indicatorwhenever an alarm signal is present at one of the inputs to the encoderwhereby the indicator distinguishes between the display of a number inresponse to the appearance of an input signal and the display of anumber in response to the disappearance of an input signal.

4. A receiver according to claim 2, in which the digital display devicefurther includes a printer for printing the said input number displayedby the counter.

5. A receiver according to claim 2 in which the encoder includes a diodematrix of perpendicular coordinate lines, the output of each gatingcircuit being connected to the junction of a respective pair of diodesin the matrix such that an output is obtained from the correspondingpair of coordinate lines which intersect at the junction, the twocoordinates together representing the two digits of the numbered inputline to be displayed.

6. A receiver according to claim 2 in which the counter includes meansfor hunting synchronously for each of the pair of coordinates.

7. A receiver according to claim 2 in which the counter comprises a pairof electromagnetic decade counters arranged to give a two digit decimaloutput display. a first of the decade counters hunting for the leastsignificant coordinate and the second decade counter hunting for themost significant coordinate of the number to be displayed.

1. A receiver for use in a security alarm signalling system in which apredetermined number of remote stations are each connected to a centralreceiving station by respective pairs of wires, each remote stationbeing identified by a different predetermined number, and the receiverincluding a multiple input encoder, each input of said encoder beingconnected, when in use, to a respective pair of wires from one of thenumbered remote stations, and the receiver also including a multipleinput binary store; gating means connected between the outputs of saidbinary store and corresponding inputs of said encoder; scanning meansfor periodically scanning the inputs of said encoder, said scanningmeans including enabling means for periodically enabling each of saidgating means in turn; said encoder including means responsive to achange in the signal level on any one of its inputs for generating acOded output signal representative of the number of the remote stationto which the input is connected, and a digital display device includingmeans for converting the coded output into a digital read-out of saidnumber; and means responsive to the presence of a signal in said encoderfor inhibiting the enabling means until the signal has been encoded andread out on the display device.
 2. A receiver according to claim 1 inwhich the digital display device includes a counter, and the receiverfurther includes an oscillator for feeding pulses to the counter inresponse to a detected change of signal level on one of the inputs tothe encoder, a coincidence detector connected to compare the output ofthe encoder representing the number of the remote station associatedwith the change of signal level with the number present in the counter,and inhibiting means connected to receive an output from the coincidencedetector when the two numbers being compared are equal for inhibitingthe supply of pulses to the counter such that the final number displayedby the counter represents the number of the remote station.
 3. Areceiver according to claim 1, further including a clear line indicatorconnected to receive an energising signal from a control circuitwhenever a change in signal level has been detected at one of theencoder inputs, and means for inhibiting operation of the indicatorwhenever an alarm signal is present at one of the inputs to the encoderwhereby the indicator distinguishes between the display of a number inresponse to the appearance of an input signal and the display of anumber in response to the disappearance of an input signal.
 4. Areceiver according to claim 2, in which the digital display devicefurther includes a printer for printing the said input number displayedby the counter.
 5. A receiver according to claim 2 in which the encoderincludes a diode matrix of perpendicular coordinate lines, the output ofeach gating circuit being connected to the junction of a respective pairof diodes in the matrix such that an output is obtained from thecorresponding pair of coordinate lines which intersect at the junction,the two coordinates together representing the two digits of the numberedinput line to be displayed.
 6. A receiver according to claim 2 in whichthe counter includes means for hunting synchronously for each of thepair of coordinates.
 7. A receiver according to claim 2 in which thecounter comprises a pair of electromagnetic decade counters arranged togive a two digit decimal output display, a first of the decade countershunting for the least significant coordinate and the second decadecounter hunting for the most significant coordinate of the number to bedisplayed.